(a) Field of the Invention
The invention relates to an ocular optical system simulating method and a simulating apparatus for simulating how things are seen when the outside world is observed through a lens system placed in front of the eyes.
(b) Related Art
An apparatus has been described in Japanese Patent Laid-Open No. Hei. 8-266473 applied for previously by the assignee of the present application. In this prior application, there are described an ocular optical system simulating method and a simulating apparatus for simulating how things are seen when the outside world is observed through a lens system placed in front of eyes.
The apparatus described in the above-mentioned publication simulates an image of scenery in a scope which can be visualized by turning eyes while wearing spectacle lenses, by computations including computing the Point Spread Function (PSF). The disclosed apparatus and method have enabled simulation of the sight of scenery in a wide angle involving rotation of human eyes while wearing optical lenses such as spectacle lenses.
Unpleasant sensations of fluctuation, deformation and blur in wearing progressive addition lenses (PAL) are obtained in certain cases, even though these lenses fulfill the function of accommodating far and near distances. Therefore, suppression of these unpleasant sensations to the greatest degree possible while accommodating for the far and near is desirable in designing a progressive addition lens. To this end, it is most desirable for a designer himself to know whether the designed lens is accompanied by unpleasant fluctuation, deformation and blur. The above-mentioned conventional ocular optical system simulating method is very useful for certain purposes because it can simulate scenery in a wide angle involving the rotation of human eyes in wearing optical lenses such as spectacles. However, the above system cannot simulate the deformation, blur, etc., which the wearer may feel in reality by also taking human perception into consideration. Therefore, these methods have not always been sufficient to fulfill the purpose of allowing the designer himself to know in advance what kind of deformation and blur the wearer actually perceives when the wearer wears the designed lenses. Still more, this system cannot deal at all with the fluctuation, which is considered to be the most serious problem in actually wearing lenses.
An image of the outside world perceived by a human through the eyes is not considered to be an optical image formed on the retina of the eye in accordance with optical principles. That is, the distribution density of photoreceptors on the retina is high around the fovea and is low at peripheral parts. Accordingly, if a strictly optical image formed on the retina is perceived, it must be perceived as an image which is clear only around the center and is unclear at the periphery even when the optical image is ideally formed. However, one can sense that one can see clearly anywhere within a field of vision as long as one has healthy eyes. This is because the operation of perception is not a simple operation of detecting the optical image projected on the retina as it is, but is based on the result of a complex system of processing neural information on and after the retina.
According to the research of the inventors, although such perception may not be simulated directly, it has become clear that the result of the perception may be reproduced approximately by image processing based on certain assumptions found by the inventors.
The present invention has been devised based on the background described above and its object is to provide an ocular optical system simulating method and a simulating apparatus which enables simulation of how things are seen, with fluctuation, deformation, blur and the like, while wearing a lens system such as a progressive addition lens.